Crystal detector



Feb. 19, 1929,

F. E. MANN CRYSTAL DETECTOR original Filed May 9, 1925 Patented Feb. 19, 1929.

UNITED STATES FREDERICK E. MANN', 0F CHERRYDALE, VIRGINIA.

CRYSTAL DETECTOR.

Application filed May 9, 1925, Serial No. 29,126. Renewed July 5, 1928.

This invention relates to improvements in crystal detector constructions for radio receiving sets.

In the use of the usual mineral crystals in t-he radio receiving sets as detectors, it is well known that these crystals usually have a number of substantially sensitive spots at different points on the surface of the crystal, and that due to the complex formation of the surface of the crystal, it is often difficult to place the contact springs on this surface and find one of the sensitive spots after which the proper contact pressure between the crystal and the contact spring can be obtained for obtaining the best results in amplifying and detecting radio signals.

This invention is designed to simplify the setting and adjustment of the Contact springs relative to these sensitive spots of the crystal, in order that the highest efficiency of operation of the crystal may be obtained in a radio receiving circuit.l

An object of the invention resides in providing a construction having the above stated qualities, which is a substantial improvement over the construction shown in the co-pending application, Serial No. 675,676, filed November 19, 1923.

A further object of this invention is to provide a crystal detector construction, wherein the crystal holder is movably mounted on a support and adjustable by independent means in any one of a plurality of different planes arranged in angular relation for providing a r proper adjustment ofthe crystal relative lto the contact spring, after the contact spring has been engaged with the crystal, in order to vary the contact pressure between the spring and the crystal surface, to attain the most efficient setting thereof.

A further object of the invention resides in providing a suitable supporting structure mounting a spring contact member adapted to be engaged with a crystal, suitably mounted in a crystal holder carried by the supporting structure, which is movable vthereon, and suitable and independent adjusting means for the crystal holder, operable in a convenient manner to produce micrometric adjustments of the crystal., relative to the contact spring, to vary the pressure of the springs on the surface of the crystal, with mic-rometric ineness, in order to obtain the highest eiiciency of operation of the detecy tor in a radio receiving circuit.

scription, and in the claims, directed to apreferred form of the invention, it being understood, however, that various changes in the size, form, and assemblage of the parts may be made, without departing from the spiritr or scope of the inventionv as set forth herein.

In the drawings, forming a part of this l application,

Figure 1 is a side elevation of the improved crystal detector construction, showing a. portion of the cover broken away.

Figure 2 is a horizontal sectional view, taken on the line 2-2 of Figure 1. y

Figure 3 is a bottom plan view of the detector construction.

Figure et is a vertical sectional View through the assembled detector structure.

Figure 5 is a detail sectional view of a portion of the crystal holder, showing the mounting for the plunger which is projected against the crystal to hold it against the adjusting screw within the crystal holder.

Figure 6 is a disassembled perspective view of thev crystal holding mounting part, which cooperates to produce a movement of the crystal holder in a vertical plane passing through its aXis.

Figure 7 is a detail sectional view, showing the manner of mounting the crystal holder in the base to permit its vertical movement and at the same time prevent a rotative movement, due to the operation of the cam structure shown in Figure 6.

Figure 8 is a diagrammatic illustration of a portion of the crystal for illustrating the character of the surface of the crystal with which the contact spring engages and the advantage of providing a movable crystal holder adjustable in a plurality of angularly arranged planes.

1 indicates the base member or support for the detector, which is formed with an upwardly projecting cylindrical extension 2, for rotatably receiving an operating ring 3, retained on the cylindrical extension by the rim 4 of the glass cover 5, adapted for removable connection with the base, through the medium of suitable separable fasteners, indicated by the numeral G. At one side of the central portion of the cylindrical projection 2 on the base member or support is mounted a post member i', having a tubular extension split longitudinally thereof, indicated by the numeral 8, for adj ustably receiving the arm 9 having the. curved upper end to which is rcmovably secured the contact spring l0, which is adapted to engage the crystal. Any form of contact spring or wire element may be used for cooperation with the crystal in rectifying the current in a radio receiving circuit, which is well known in the art, and which may be used in place of the spring structure, illustrated in the drawing.

An axial bore 1l is provided in the cylindrical projection 2 of the base member, which receives a sleeve member 12, for sliding movement therein, which is held against rotation by the rib and slot connection .indicated by the numeral 13 in llicure i", the lower end ol the sleeve being` in an lar relation with respect to the axis as iiimicated at lll, for cooperation with the cam l5, carried by the operating lever ld A. crystal receiving cup li' which is liereii'iafter termed the crystal hold er is provided with an axial e tension i8. in the form of a rod or shaft, which rotatably fits within the sleeve l2 and extends through the opening 19, in the cam and operating lcver l5 and 16 respectively. This extension 1S projects substantially below the operating lever 16, for the cam, as clearly illustrated in Figure il, and receives by threaded connection a nut 20, which secures the coil spring 2l, under tension between the washers 22, so as to hold. the crystal receiving cup or holder l? in engagement with the upper en d of the sleeve l2. The operating lever i6 projects through a slot formed in the cylindrical extension 2 of the base member as indicated at 23 and is received by the operati ng ring 3, rotatably mounted on the cylindrical extension 2 as above described. This provides a means for operating thel cam l5 sc that upon the manual rotation of the operating ring 3, the lever 16 will be rotated, for rotating the cam, l5, relative to the sleeve l2, which will effect a vertical adjustment of the crystal holder 17. The crystal holder 17 may be rotated freely, by manual operation, while the portion for receiving the crystal 2li is substantially larger than the usual sir/,e of the mounting for crystals, as sold in commerce. This is for the purpose of permitting a lateral adjustment of the crystal within the cup l? by means of the set screw 25, in order to provide for a movement of the crystal in a plane substantially at right angles to the movement effected by the operation of the operating ring 3. ln order that the crystal will be maintained against the set screw 25, a plunger 26 provided with a notched end 27, for engagement with the periphery of the crystal mounting, which is projected by the coil spring 28 seated within A strip 32 electrically connects the projec? tion 18 of the crystal holder., n the bind ing post 33 on the base l, for receiving the other side of the circuit connection of the receiving circuit.

Referring particularly to Figure 8, a section of a crystal is indicated at 341-, showing on an enlarged scale an example of the surface formation of the crystal as indicated by the numeral 35, in which a plurality of substantially flat angularly arranged surfaces of various size are pressed.` lWith a surface structure of this character which is considerably more complex than the average crystal structure, it will be seen that by the manual adjustment of the contact spring` 36, it would be substantially difficult to obtain the proper pressure of adjustment of the end of the spring on the surface of the crystal, when a sensitive point is reached on ,the surface of said crystal, in order to obtain ref sults of the highest efliciency, for receiving and rectifying purposes, in a radio circuit. This difliculty appears vto present the greatest disadvantage in the use of crystal recti fiers. Itis for this reason that various forms of contact springs are used, some of which include a large number of fine wires assembled in a group and pulled apart for engagement with different portions of the surface of the crystal at the same time. Even this character of construction has been unsatisfactory for best results, which have been found to be highly obtainable by the present invention. For instance, the adjustment of the set screws 25 moves the crystal in a plane at right angles to the plane of the contact spring 36, in either direction, as indicated by the line and arrows 37, while the operating ring 8 in operating the cam 15 and sleeve 12 produces a movement of the crystal in a vertical plane, as indicated by the `arrow 38 which is substantially at right angles to the movement of the crystal in the line of the arrow 37. In addition to this, the rotation of the crystal holder will produce a further adjustment, as indicated diagrammatically by the arrow 39. This provides a plurality of adjustments in different angularly arranged planes, so that in the use of the crystal for a detector in a'radioreceiving circuit, with these three adjustments as above set forth, a very fine Contact pressure between the spring 36 and the surface of the crystal 34 can be obtained, which is found to be highly desirable to obtain the most efficient results.

In the operation of the crystal detector, in

order to obtain this point of highest efliciency, y

l quires not only a vertical adjustment in the plane of the arrow7 38, but also a horizontal adjustment in the plane of the arrow 37, in order that the crystal may be moved to carry the surface 40 in a lateral or vertical direction,

so that the spring contact 36 extends substantially vertically downward and touches is engaged with the surface of the crystal is not the most sensitive point, by lowering the crystal slightly in the plane of the arrow 38 and then moving it laterally or giving it a slight rotation in the plane of the arrows 37 or 39, this surface 40 can be again engaged to accurately find this most sensitive spot and at the same time vary the pressure of contact of the spring 36, on the surface of the crystal with micrometric ineness, in order to get the greatest efficiency of rectication of the signal received in a radio receiving circuit, in which the detector is connected. Without this character of adjustment of a crystal, relative to a spring contact, it is substantially impossible to obtain thev micrometric variation of contact or point of contact of the spring 36, with any desired surface formation of the crystal.

IVhile a special construction of crystal detector has been described, in which specially constructed elements have been provided for producing the movement of the crystal in a vertical plane indicated by the arrow 38, a horizontal plane indicated by the arrow 37 or rotated as indicated by the arrow 39, it is to be understood that the specific embodiments of these constructions are merely for the purpose of disclosing one example by which the adjustment may be carried out, and that it is entirely within the scope of the present invention to provide any other desired structure of specific elements for carrying out these relative adjustments of the crystal in the yangular relation illustrated and described, or in other angular relations apparently desirable for the purpose of the invention.

What is claimed is: n

l. A crystal detector, comprising a support, a sleeve member slidably mounted 1n said support, a cam member movably mounted in said support and engaged with said sleeve member for moving the sleeve member in the movement thereof, a crystal holder rotatably mounted in said sleeve member and slidable therewith, a contact member mounted on the supp`rt for engagement with a crystal in said holder, and manually operable means for moving said cam member.

2. A crystal detector, comprising a support, a sleeve member slidably mounted in said support, a cam member operably mounted in said support for operating said sleeve member, a crystal holder rotatably mounted in said sleeve member, and'manually operable means carried by said support movable for operating said cam member.

3. A crystal detector, comprising a support, a sleeve member slidably mounted in said support, a cam member mounted on said support for operating said sleeve member, a crystal holder mounted in said sleeve member, and manually operable means for operating said cam member.

In testimonyy whereof I aix my signature.

VFREDERICK E. MANN. 

